In the early 1950's , most post-war German could only afford the small 250cc Goggomobil T250, if that at all.

However- Germany's economy began to improve and Hans Glas and his engineers determined that there was a market for a car that was "somewhat" larger than a Microcar, but not as large (or expensive) as a Volkswagen.

The car was unveiled in 1957 as the "large Goggomobil", it had either a 600 or 700cc engine and plenty of room for a family of four and their luggage.

To try and distinguish it from it's Microcar predecessors,
The T-250,T300,T-400 the car was actually given a name:
The Glas ISAR T-700

It was also known as the "ROYAL" in the UK.

The name was changed to ISARD for some foreign markets when it was discovered that "Isar" meant "foolish" in some language.(this has not been confirmed)
Also- the short name "Goggo" is apparently slang for something undesireable in French, so eventually the car was known as the GLAS Isard apparently just to be safe